Electric control mechanism for air-brakes.



H. ROWNTREE. ELECTRIC GONTRGL MEGHANISM FOR AIR BRAKES.

APILICATION FILED JUNI-129,1908.

Patented Jan. i5,

@XM/Mmmm@ HARLE OIE GHXCGO, ELLINOS, ASSIGNZ El@ E'TGNAL PN."

ATIG v COMANY, A CORPORATION OF WEST VKRINIA.

ELECTRG CONTRGL MECHNSM FR LfERHE T0 all tollem if may concern Re it known that i, HARoLn Rown'rnn, a citizen of the United States, residing at Chicago, county of Cook, State ot' Illinois, have made a certain new and useful invention in Electric Control Mechanism for Air-Brakes7 of which the following is a specification.

The invention relates to elect-rio control mechanism 'for air brakes.

The object ot the invention is to provide means in an air brake system for controlling electrically the supply ot pressure to the brake cylinder.

A further object is to provide an electric control mechanism for air brake systems wherein the pressure in the brake cylinder is automatically maintained at uniform degree corresponding to the posit-ionof a oontrol handle for controlling the electric circuits ot' the electric devices.

A further object. oithe invention is to provide means whereby an electrically operated control of the brake cylinder pressure operates in conjunction with an ordinary triple valve in such manner that in case the electric control should .fail in its intended operation the triple valve. would operate in the usual manner to etlectthe desired control of the brake cylinder pressure.

A further object is to provide an electric control for air bralre systems wherein simultaneous operation ot the brake mechanism is eilected on all the cars of a train, and wherein the brake pressure on eachA car bears a definite relation to the position ot the control handle regardless ot' leakage.

Further objects of the invention will appear more fully hereinafter.

The invention consists substantially in the construction, combination, location and relative arrangement of parts, all as will be more fully hereinafter set i'orth. as shown in the accompanyinpY drawings. and .tinally pointed out in the appended claims.

The single vier: oil the acconipanyingn drawing shows somewhatI diagrannnatically an electric control mechanism for air brake systems, embodying` the principles oit my invention.

Referringy to the accompanying drawing:

` 1 designates a train pipe t'or supplyinp` the pressure to the various cars ot' the train. Upon each car is. arranged the ordinary auX- iliary reservoir or tanlr Pathe 1oralte cylinder Specification of Letters Patent.

Application fried June 29, 1968.

Patented Jan. tei, 1%2.

serial. No. ceases.

8 and the triple valve Il. The brakemechanism is not illustrated as it will he readily understood that any usual or well known 'construction and arrangement ot brake mechanism may be employed. Pressure is supplied from the train pipe 1, to the auxiliary reservoir or tank 2, in any suitable manner, as for instance, through. a pipe or connection 5 in which is arranged a check valve 6, in the ordinary manner, @ne end of the triple valve casing is connected freely by a pipe 7 .to the train pipe. `The pressure thus supplied to the triple valve casing is exerted upon the triple valve 4: to normally maintain the triple valve pressed toward the other end of the triple Valve casing and such pressure is arranged to be opposed by an opposing' pressure, such for instance, and as embodying one form of my invention, as afforded by a spring 8.

Except as hereinafter noted the parts so tar described may he of any suitable o'r well known construction and arrangement.

11 and 12 designate solenoid coils.l These coils are mounted upon the casing 13 having a longitudinal here therethrough, and cooperatingwith each solenoid coil 11, 12, is a core 14, 15, respectivelysaid cores operating within the 1oore of casing.r 13. Each core 14, 15, is proriced with a. longitudinal bore or channel 1 6 therethrough, and springs 17 arranged within the bore ot casing 13 engage the inner ends of the cores 14e, 15, and normally operate to press said cores outwardly. Other means may he employed for normally maintaining the cores withdrawn more or less or partly from their coils.

The cores 14, 15, are provided with openingejs or ports 1S, 19, respectively 'adapted to be brought into and out of register with pipes 3() and l21, respectively. That is, the port 19 formed through the wall oi core 15` is adapted to be brought into register with connection Q1. whenever the solenoid "coil 12 is energized so as to draw said core 15 into said coil andagainst the action ot its retract-ing` means. as 17, and when said coil 12 is deenergized, or its circuit broken, the retracting means 17 serves to withdraw core 15 from said coilz thereby carrying port 19 out of register with connection 21. Similarly when coil 11 is energized core le action of its reti-acting means 17, thereby bringing port 18 into register with connection 30. And when magnet 11 is deenergized, or its circuit broken, its retracting means 17 serves to withdraw core 1e `from the magnet coil 11, thereby carrying joined and extending through connection 24 to the triple valve casing. In practice and in order to protect the windings of magnet coils 1]., 12, from any'dampness or moist-ure that might be present in the compressed air, I prefer to arrange said coils on the outside of the casing 13, as shown and hence out of access of the coml pressed air thereof. To this end said coils are Wound upon sleeves 25 connected to or forming part of the casing 13.

1f desired and in order to prevent both solenoid cores 14, 15, from being simultaneously drawn into their respective coils I interposel rod 2G between the juxtaposed or proximate ends of said cores, said rod being of suflicient length to permit either one of the cores to be fully drawn into its` coil, but preventing both cores being drawn into their coils at the same time. From pipe' connection 2li-.leads pipe 27 to one end of the cylinderv 28, in Which operates a piston 29, having a rod 31 connected thereto and operating'through the other end of said cylinder. The pressure supply to the cylinder 28 through connection 27 is opposed b y suitable means as forinstance, spring 32, the tension of said means normally operating to move piston 29 toward .that end ot' cylinder 28, into which pressure is delivered through pipe 27. The piston rod 31., carries a cross-head 33 to which are connected contact strips 34,- 35. These strips are separated from each other and a neutral or insulated block 36 is placed between the proximate ends thereof. Cooperating With the contact strip 34 is a contact 37, and similarly coperating with strip is a contact 38. Coperating With the strips 34: and 35 are the series or' magnets 39, corresponding with the various degrees ot pressure which it is desired to maintain in the brake cylinder. Thecircuits of vthese various magnets, and of the electromagnet coils 11, 12, are controlled by a control handle 41, operating over a series of contacts 12, and which correspond, in like manner to the magnets 39, with the vari. ous degrees of pressureto be maintained in the brake cylinder., Thus it Will be noted. that the various contacts 4t2-and also the corresponding magnets 39 are marked respectively, 0, 10, 20, 30, "40, and

,350, thereby indicating that when the control handle 41 is moved into Contact with Itis to be understood that the arrange-i ment above set forth is the arrangement on each car of the train, except that the con trol handle il and the contacts 42 may, if desired, in case of a train of cars be located on the engine, or other convenient point, to be operated and controlled by the engineer or other proper party.

The triple valve l is provided with a passage 43, for controlling the communication of connection 2st, through pipe or other connection 44C, With the brake cylinder 3. The triple valve is also provided with a passage 45, for controlling communication between the brake cylinder pipe 4e, and the eXhaus- .tive connection tt, or to the connection 47, with the auxiliary reservoir.

, It is to be understood, of course, that the train pipe 1, extends throughout the length 0I the train of cars, in case of the use ot my invention on trains', the sections thereoi:l on each car being connected up to each other at their ends .by hose couplings or otherwise, in the usual'manner.`

Current is supplied to the circuits of the sets or series of magnets 39, and the solenoids 11 and 12, from any convenient source. 1 have .shown a connection 51 which may be considered the main Wire connect-ion, and which is connected to the contacting end 52 of control lever l1. Each of the cont-acts 42 from which the control lever operates, is connected to one of the conductors 53, the various conductors 53 extending throughout the train. On each car of the train branch conductors 58 extend from the conductors 53 to and through the various magnets 39, and thence to the common return Wire or ground connection 55. Ordinarily this return connection may be accomplished through some part or" the framing of the car. Each inag- Y net 39 is provided with a pivoted armature 56, which, When the magnet is energized, is rocked so as to carry one end or portion thereof into cooperative contacting relation with thecontact stri'p 3st or 35, as the case may be, arranged adjacent thereto, and When such magnet ris denergized the armature falls back, thereby breaking suchconnection iso here

2- strips 34, 35. The contact nlained, is designed to be in ting relation with respect to i 3d, and similarly the conwtant contacting relation contact strip 35. The oid 11 is completed :trom ough conductor 57, and urn conductor 80, and simicircuit of solenoid 12, is conin contact 37, through. conductor` ence to the common return 80. Each ot' the conductors 53, at the point where it enters the Winding of, its magnets 33 is also connected to the armature 56 there t, so that the moment the magnet is energized, and its armature attracted, current is permitted to pass through such arma-y` ture 56, to the portion thereot` Which contacts with its associated strip 34, 35, and thence through the `windings of one or the other of the solenoid coils 11, and 12, accord- .ing to the relation of the particular magnet 39, with vreference to one or the `other of said strips 3e, 35, While at the same time, current is permitted to continue to How through the coils of the magnet 39.

The operation oi' the apparatus Will be readily understood from the foregoing de scription, and is as follows: Supposfnby way of illustration, that there is no pressure in the brake cylinder. In this case the piston 29, in cylinder Q3, will beheld at the limit ot its movement toward that end of said cylinder which is open to the brake cylinder pressure. ln this position the contact strip will be held in operative relation with all ci the associated magnets 39, except that the magnet 39 which is marked 0 in this case will be in contact With the neutral point 36. Non' suppose control handle 41 is moved into the position thereof indicated in the drawing to complete circuit connecti'on to the contact 42 which is marked 10 Thereupon circuit is completed from the main 'conductor 51 through contact member of the control handle, the contact-1Q which is marked thereby indicating a brake cylinder pressure of ten pounds, thence circuit is completed through one of the wires 53 throughout the train and vthrough one of the-Wires 58, in each one of the cars of the train to the corresponding magnet 39 which is marked 10, and also vtlirruigh the armature of said magnet, when the latter is attracted, to the contact strip 35, a portion of the current flowing through lsaid contact strip 35, contact 38, Wire 57, electromagnet 11 and return 58, and a portion ot the current flowing through the coil of the magnet marked 10, and to return 55. The resulting energization of solenoid 11 effects a movement of its core valve14 into such coil, thereby bringing port- 18 of such core valve into more or less complete register with the pipe or other connection from the tank Q, and hence admitting pressure through the bore 16 of said valve core, connection 23, connection 2st, passage 43 of the 'triple valve and brake cylinder conncction ell. At the saine time a corresponding pressure is admitted through aconnection 2 to cylinder 28, thereby shitting piston '29, and correspondingly shitting the position ot contactstrip with reference to the magnet 39 marked 10, as above noted. As soon as the desired ten pounds is thus admitted to the brake cylinder and to cylinder 28, the contact strip is shifted to such a point as will cause the armature of the magnet marked 10 to ride oil of strip 3o, and

to contact with neutral point 36, thereby breaking the circuit connection of electromagnet 11, and hence causen return or Withdrawal movement of the core valve 14, under the iniuence of its retracting means 17 t-o out oli" position. It' thepressure admitted to the brake cylinder and to the automatic control cylinder 28 is in excess of the desired ten pounds*V the piston Q9, will be shifted a distance sufficient to bring contact strip 34 into cooperative relation with respect to the armature of the magnet marked 10 to etfect a closing of the circuit through said strip 34 and contact 37 of the solenoid 12, thereby actuating the core valve 15 into position to cause port 19 to register with exhaust connection21, thereby opening the brake cylinder' and also thev automatic control cylinder 28 to exhaust, and

hence reducing the pressure therein, at least to the point Where the armature ot' magnet marked '10 is brought into contact relation with the neutral point 3G, which will result in breaking the circuit of solenoid 12, and the return ot' the core valve thereof to cut oli position. Of course it is to be understood that all of the magnets marked 10 in the example above given, on all of the cars remain energized so that the automatic regulation and control of the brake pressure is maintained throughout all of the cars` throughout the train. The action is also simultaneous on all of the cars, although the regulating apparatus including the automatic control cylinder, the set of magnets 39 and the electrically operated valves 14 and 1,5 of each car are independent of the corresponding parts on the other cars.

It is obvious that the arrangement above described is equally1 Well adapted for use on single cars. ln this case a control handle 41 Will. be located at either ,or both ends of the car. The apparatus above described remains the same with the exception that the circuit Wires 53 will not connect up with any other car.

It will be seen from the foregoing description that 'the automaticl control of the air brake-pressure is accomplished electrically.

It will also he seen that the brake pressure bears direct relation to the position of the control handle so that the engineer or other attendant manipulating said control lever can determine by reference to the position of said handle the degree of pressure in the brake cylinders. It will also be seen that in case of leakage at any point in the system the desired predetermined pressure is maintained in the brake cylinder, dependent in degree upon the position of the control handle 42, whatever such leakage may be, or wherever 1t may occur throughout the system, for the reason that through variation in' the pressure within cylinder 28, and such pressure will vary with any variation in the brake cylinder pressure which might be caused by leakage at any point in the system, the circuit ot one or the other of the solenoids l1, 12, will be completed or broken,.

handle 4l, with the Contact 42, which isl marked 10, it will be readily understood that the same method of operation is involved when the conductor part 52 of control lever 41 cooperates with either one or the other of contacts 42, the dili'erence be-I ing merely in the particular magnet 39,

the circuit of which is completed. rIhe action remains the same, the control of the circuits of the solenoids li, l2, being subject to the variations of pressure in the automatic controlling cylindervQS and that pressure being dependent upon the pressure which it may be desired to maintain in the brake cylinder.

It tor any reason the supply of electric current for operating` the control of the brake system should be eut oit, it is important that the engineer should still retain control of the brakes. It is also important that in case the train should pull apart that the brakes should instantly be applied. To

enable these objects to be accomplished, I so arrange the. mechanism that the electric control devices are operative only so long as a certain pressure is maintained in the train pipe, and as soon as the train pipe pressure is reduced below this point, the electric control devices immediately beeome inopera tive, if they are not already so, and the iurther control of the brake pressure and of the brake mechanism, is effected entirely through the triple valve 4, by varying the pressure in the train pipe in the ordinary manner. Suppose for example that the remesa pressure normally carried inv the train pipe is ninety pounds, and that this is the desired predetermined pressure at which the electric control devices are o erative. This pressure, through the pipe. admitted to the end of the casing in which operates the four way valve 4, and which I have called a triple valve, is sufficient to hold the said valve 4 against the opposite end ofthe casing and in position to maintain the spring 8 under the limit of its compression. In thisiposition the pipe 24 from the casing of the electric control valves is in communican tion through the port 43, with the pipe 44, to the brake cylinder. The moment, however, the train pipe pressure is reduced, either by the operation of any suitable form of control valve or by the train pulling apart, or otherwise, the valve 4, begins to move under the influence of spring 8, toward the opposite end of the casing. The rst eii'ect of this movement of said valve is to cut oit the communication of pipe 24, with passage or port 43, thereby cutting 0E all communication between the electric control valve and the brake cylinder. I propose to so proportion the strength of spring 8, thatas soon as the pressure in the train pipe has fallen, to, say, seventy five pounds, the valve 4 will have moved sufficiently far, under the intiuence of spring 8, to entirely cut oii` the communication between pipe 24 and passage 43, and at the same time to open communication between pipe 44, passage 43, and passage 45, to the exhaust pipe connection 46, thereby opening the brake cylinder to exhaust. A further reduction of train pipe pressure to, say, sixty pounds, will result in a further movement of valve 4, into position to cut off the communication of passage 45, withthe exhaust 46, and to open communication between said passage 45, and the auxiliary tank 2, through pipe 47, thereby opening the auxiliary tank to the brake cylinder, thereby instantly applying`the brakes. As long, therefore, as the full train pipe pressure is maintained in the train pipe the electric control devices areoperative and the pressure in the brake cylinder will be proportioned to the position ot' the engineers control handle thereby maintaining the pressure in the brake cylinder in constant relation to the posit-ion of the control handle regardless oi any leakage at any p oint in the system, but as soon as the train pipe pressure is reduced below the' predetermined degree, the electric control valve is cut ott and rendered inoperative and the brake cylinder is opened to exhaust. Further reduction of train pipe pressure causes auxiliary tank pressure to be admitted to the brake cylinder. l I have not shown any form of controllin valve for the train pipe as such valve forms no part of my present invention, and any denoiasce sired or Well known type or term 'of engineers control valve may be used to control the pressure in the. train pipe.

Having new forth the object and nature ot' mv invention, and a construction and arrangement embodying the principles thereof, what l claim as new and useful and of my own invention and desire to secure loy Letters Patent is:

l. In. an air hral-:e system, a brake mechanism and electrical devices for maintaining any desired predetern'iined pressure supply to the 1uralte mechanism, circuits for said electrical devices, and means for automatically controlling1 said circuits.

2. In an air brake system, a brake mechanism, and electrically operated means for controlling the supply andiexhaust of pressure medium to and troni the liralte mechanism, said controlling means operating to automatically maintain any desired. predetermined pressure supply to the brake mechanism.

3. In an air hralte svstem, a liralte mechanism, electrica-l d ces tor controlling the exhaust of pressure from said liralte mechanism, and ,means for automatically controlling the circuitot said electrical devices to maintain unitorin i ssure in the loi-alte mechanism varyin, in amount according to the relative Anosition 4, i the control lever.

a. ln an air liralte system, a loralte mechanism, electrically operated devices for controlling the supply and exhaust of operating medium to and from the hrale mecha-- nism, and means operating to automatically control the circuits ot said devices to maintain predetermined pressures in the brake mechanism.

5. In an air brake system, a lnrifc mechanism, valves tor controlling` the .siuuily and exhaust of pressure medium to and brake mechanism, electrical devices ating` said valves, and means auto controlled according` to ditterent p.

. opertically edetermined pressures for controlling the circuits of said electrical devices.

G. ln un air liralte sy.y ein, a oralte mechanism, and 'valve for cimitrolling; the supply of operating medium te said inechaniSm, an independent valve 'jor controlling the exhaust of operating medium from said mechanism, and electrical devices tor controlling said valvesl whereby the degree ot pressure in the brake mechanism corresponds to the relative positions ot the electrical devices.

7. ln an air 1uralte system, a brake mechanism, means for controlling the supply and eithaust et operating medium to and from saidmeclninisni, electrical devices for operali-ing' said col'itrolling` means, circuits -torv said electrical devices and means operated lby variations in brake pressure Jfor controlling said circuits whereby 'the de free of prestor operating the same, circuits sure in lie loralte mechanism is maintained at uniform degrees accordingl to the relative position ot' the electrical devices.

8. ln an air lifak'e system, a uralte mechanism, means t'or controlling the supply and exhaust oit pressure medium to and from said meclianism, electrical devices tor operating the same, and automatically operated devices for controlling' the circuits of said electrical devices whereby the degree ot' pressure is maintained uniorm in the hralte mechanism according to the relative position of the electrical devices.A

9. ln an air hralte system, a brake mechanism, means for controlling the supply and exhaust of pressure medium to and from. said pressure mechanism, electrical devices therefor, and means operatedby the 're medium for automatically controlling Le circuits said electrical devices whereby the degree ot pressure is maintained unitorni .in the ln'alze mechanism according to the relative position of 'the electrical devices..

l0. ln an air brakesystem, a hrale mechanism, valves for controlling' the supply and exhaust of operating medium to and from said mechanism, solcnoids 'for controlling said valves, a control lever arranged te he set to different positions correspondingj to any desired predetermined pressure, and means controlled conjointly oy said lever and by variations in the bralte pressure tor controlling` the circuits ot the solenoids.

l1. ln an air brake system, a brake mechanism a supply valve and an exhaust valve ther-eter, solenoids to control said valves, a control lever arranged to he set to d'illerent positions corresponding to any desired pressure, and automatic devices cooperating `with the control lever for controlling the circuits ot the solenoids.

l2. ln an air brakesystem, a brake mecha.- nism, supply and 'exhaust controlling valves therefor, a control lever arranged to he set to different positions to predetermine the degree ot pressure supply, electrical devices for controlling` the valves to maintain the pressure uniform al' whatever degree it may he predetermined by the position. ot the control lever circuits for the electrical devices, and means tor automatically controlling said circuits.

i3. ln an air brake system. alorake mecha-- nism, controlling),1 valves th for, electrical devices for operating the valves, circuits therefor, a control lever arranged to beset to dierent positions to predetermine the degree et brake pressure, and means operated by variations in the pressure as predetermined loy the position of the lever for controlling' said circuits to maintain the pressure uniform at the predetermined degree. i

l-fl. ln an hralre systemeJ brake mechamsm, electrical devices for controlling lthe supply and exhaust of pressurt medium to and from said mechanism, a control lever arranged to be set to diii'erent positions to predetermine the degree of pressure and means cooperating with the lever when in pressure predetermining position for controlling the circuits of said pressure controlling devices whereby uniform predetermined pressure-is maintained in the brake mechanism.

15. In an air brake system, a brake mechanism, supply and exhaust controlling means therefor, electrical devices for operating the same, circuits for said devices, magnets for controlling said circuits and a control lever and pressure operated devices cooperating therewith for controlling the circuits of said Y magnets whereby the degree of pressure in the brake mechanism is uniformly maintained according to the relative position of the control lever.

16. In an air brake system, abrake mechanism, supply and exhaust controlling means therefor, electrical devices for operating the same, circuits for said devices, magnets for controlling said circuits, a control lever for the magnet circuits and automatically movable contacts controlled by variations in the brake pressures and cooperating with said magnets 'to control the circuits of said devices whereby the degree of pressure in the brake mechanism is uniformly maintained according to the relative position of the control lever.

7. In an air brake system, abrake mechanism, supply and exhaust controlling means therefor, electrical devices for operating the same, circuits for said devices, a control handle arranged to be set to different positions to predetermine the degree of pressure supply to the brake mechanism, and means dependent upon the position of the controllever for controlling the circuits of said .electrical devices.

18. In an air brake system, abrake mechan ism, pressure medium, supply and exhaust controlling mechanisms, electrical devices for operating the same, a control lever, and means controlled accordingto the position of said control lever for automatically controlling th'e circuits of said electrical devices whereby the pressure supplied to the brake mechanism varies according to the position occupied by the lever.

19. In an air brake system, a control lever, a series of contacts with which said lever coperates, a corresponding series of magnets in respective electric communication with said contacts, automatically movable contact strips, means actuated by said magnets when energized for completing circuits through one or the other of said strips.

according to the relation of the parts, a brake mechanism, and electrical devices arranged in said circuit@ for controlling the supply and exhaust of operating medium toand from said brake mechanism.

20. In an air brake system, a brake mech-- anism, electrical devices for maintaining uniform pressure in the brake mechanism, circuits for said electrical devices, means for automatically controlling said circuits, andv means independent of the electrical devices for controlling the brake pressure.

21. In an air brake system, a brake mech.-

anism, electrical devices for controlling thel brake pressure, circuits for said electrical devices, means for automatically controlling said circuits, and Ymeans independent of the electrical devices for controlling the brake pressure. n.

22. In an air brake system, a brake mechanism, electrical devices for controlling the brake pressure, circuits for said electrical devices, means for automatically controlling 'said circuits, and auxiliary means for conA trolling the brake pressure, said auxiliary means becoming effective when the electrical devices are rendered inoperative. g

23. In an air brake system, abrake mechanism, electrical devices for controlling the supply of pressure to said brake mechanism, a control lever arranged to be set to different positions to predetermine the'degree of brake pressure, and means controlled conjointly by the position of said lever and variations in the train pipe pressure for controlling the said electrical devices. f y Q4. In an air brake system, a brake mechanism, electrical devices for controlling the brake pressure, circuits therefor, means for automatically controlling said circuits, means for controlling the brake pressure through variations in train pipe pressure, said means becoming etl'ective when the electrical control-'is rendered inoperative.

25. In an air brake mechanism, a brake mechanism, a control lever, electrical devices for maintaining pressure in the brake mechanism corresponding to the position of the control lever, circuits for said electrical devices, means for automatically controlling said circuits by variations in the'pressure and means for controlling the brake pressure when the electrical devices are rendered inoperative.

Q6. In an air brake system, a brake mechanism, electrical devices for controlling the brake pressure, circuits for said electrical devices, means operative at a predetermined train pipe pressure for controlling said circuits, and means whereby when the train pipe pressure is reduced below such predetermined degree the brake pressure is controlled independently of said electrical 4devices. i y

27. In 'an air brake system, -a brake mech'- anism, foreach car of a train, a control le- Veryarrangecl to be set todiferent positions te predeiermiie tile degree of brake pressure and mitemutie devices for maintaining uniform TiegreegA pressure in the brake 1neel1- misure of el! the eure Simultzuiea'msly 21cing 'te the reietive peeitiens of the e011- trui ier/er.

52S. in am air brake eyeteu'i, e. brake meeh- :iriih-iii Vtor mieli ear ef e train: n control lever, zii-rau .l te be eet te different positions te predeteimine the degree of brake pressure :xml eutenmti devices eeiiperating there\fvith for Iiminteiuing uniform degrees el.' pressure in the brake meeimnism of :lll the ears simultanemisly corresponding te the relative positions of ille control lever.

2S). In mi air brake system, a brake meel).- fziniem for e-.ieh ear of n train, electric-al devices for Siix'mitzmeousiy Controlling the brake pressure on all the cars of the train, controlling circuits for said electrical 'devices, a control lever, and means operated by the pressure medium, coperating with Suid lever for?" controlling the circuits of said electrical detees, whereby uniform degrees of pressure are maintained in the brake mechanism according te the relative posi-` tiene occupied by said lever.

in testimony whereof I have hereunto set my hand in the presence of the Subscribing wituesees, enl this tenth day of June A. D., 1908.

HAROLD ROWNTREE.

liVitnesses: i l

L. M. SHlELDs, J. G. MITCHELL. 

